The present invention relates to a method and an apparatus for manufacturing a photographic plate having a glass base and a silver halide emulsion layer thereon, and more particularly relates to a method for manufacturing a photographic plate which has a glass base and a silver halide emulsion layer thereon and which can be used for various photomasks.
A photographic plate having a glass base and a silver halide emulsion layer thereon is high in dimensional stability. For that reason, such a plate is often used for a photomask for an integrated circuit, which is required to be high in accuracy, a shadow mask for a cathode-ray tube, a lead frame, or various display units. In a process in which a liquid, namely, a photographic photosensitive silver halide emulsion, is applied to the glass base to manufacture the photographic plate, an appropriate quantity of the liquid is coated on the glass base, and the base is thereafter rapidly rotated so that the liquid is distributed to a desired thickness over the surface of the base. This process is of the spin type.
In another process, an elastic flexible hanger (hereinafter referred to as solid curtain), such as a plastic sheet, a foil, paper or a cloth, is attached to the bottom of a liquid feeder disposed over the moving glass base, and the base is put into contact with the lower end of the solid curtain so that the liquid flowing out from the liquid feeder is applied to the base. The latter process is of the solid curtain type.
In these conventional processes, however, the liquid has a tendency to cling to the end or side face of the glass base during the application of the liquid thereto and then separate from the base during the conveyance or development of the plate, while another part of the separated liquid clings to the mask pattern making portion of the surface of the glass base, thus resulting in a serious defect. In the application process of the spin type, the liquid is likely to cling to the glass base on the end and side faces thereof along the entire periphery of the base. In the application process of the solid curtain type, the liquid is likely to cling to the glass base on the leading and trailing end faces thereof. In each of the processes, the liquid clings even around to the lower surface of the glass base in some case.